To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations ...To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations and deposition temperatures.The microstructure of LTIC obtained at different deposition conditions was characterized using scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that LTIC is composed of both globular-like and laminar structures.Increasing the deposition temperature is propitious for decreasing the nucleation barrier-forming pyrocarbon in vapour,causing the quantity of spherical particles with a smaller diameter to increase and the texture of the outer layer around carbon blacks inside the spherical particles to decrease gradually.Increasing the propane concentration also made the globular-like fracture morphology more obvious and caused the laminar structure to gradually disappear.Pyrocarbon formation is dominated by a surficial growth mechanism at lower propane concentrations,while gaseous nucleation mechanism is more dominant at higher propane concentrations.展开更多
基金National Natural Science Foundation of China,grant number:50975070grant sponsor:Zhejiang Provincial Science Foundation of China,grant number:LY12E05002
文摘To investigate the microstructure and deposition mechanism of low-temperature isotropic pyrocarbon(LTIC),chemical vapour deposition was conducted in a steady-state fluidized bed using different propane concentrations and deposition temperatures.The microstructure of LTIC obtained at different deposition conditions was characterized using scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that LTIC is composed of both globular-like and laminar structures.Increasing the deposition temperature is propitious for decreasing the nucleation barrier-forming pyrocarbon in vapour,causing the quantity of spherical particles with a smaller diameter to increase and the texture of the outer layer around carbon blacks inside the spherical particles to decrease gradually.Increasing the propane concentration also made the globular-like fracture morphology more obvious and caused the laminar structure to gradually disappear.Pyrocarbon formation is dominated by a surficial growth mechanism at lower propane concentrations,while gaseous nucleation mechanism is more dominant at higher propane concentrations.
